If a spring is stretched 4m from its starting length when 20n of force is applied, then how much work (in joules) is done by the
1 answer:
ANSWER:
250 J
STEP-BY-STEP EXPLANATION:
F = 20N is required to stretch the spring by 4 meters
We know that the force is equal to:
We solve for k (spring constant):
The work done in stretching the spring is given by the following equation (in this case the stretch is 10 meters:
The work required is 250 joules.
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Answer:
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1) 4 forces
2) 165 N
3) 225 N
Explanation:
1)
There are in total 4 forces acting on the bicylist:
- The gravitational force on the byciclist, acting vertically downward, of magnitude , where m is the mass of the bicyclist and g is the acceleration due to gravity
- The normal force exerted by the floor on the bicyclist and the bike, N, vertically upward, and of same magnitude as the gravitational force
- The force of push F, acting horizontally forward, given by the push exerted by the bicylist on the pedals
- The air drag, R, of magnitude R = 60.0 N, acting horizontally backward, in the direction opposite to the motion of the bicyclist
2)
The magnitude of the net force on the bicyclist can be calculated by considering separately the two directions.
- Along the vertical direction, we have the gravitational force (downward) and the normal force (upward); these two forces are equal in magnitude, since the acceleration of the bicyclist along this direction is zero, therefore the net force in this direction is zero.
- Along the horizontal direction, the two forces (forward force of push and air drag) are balanced, since the acceleration is non-zero, so we can use Newton's second law of motion to find the net force on the bicylist:
where
is the net force
m = 75.0 kg is the mass of the bicyclist
is its acceleration
Solving, we find the net force:
3)
In this part, we basically want to find the forward force of push, F.
We can rewrite the net force acting on the bicyclist as
where:
F is the forward force of push
R is the air drag
We know that:
is the net force on the bicyclist
R = 60.0 N is the magnitude of the air drag
Therefore, by re-arranging the equation, we can find the force generated by the bicylicst by pedaling:
Answer:
-1.2 kg - m/s
Explanation:
And we need to find out the change in momentum of the body . Here ,
- velocity before collision (u) = 10m/s
- velocity after collision (v) = 2m/s .
We know that momentum is defined as amount of motion contained in a body . Mathematically ,
Therefore change in momentum will be,
Since the direction of velocity changes after the collision , the velocity will be -2m/s .